It is estimated that at least about 42% of Americans between the ages of 52 and 64 and 73% of Americans between the ages of 65 and 74 get cataracts. A cataract is a clouding of the eye's lens that impairs a person's vision and, if left untreated, causes blindness. As a result, each year approximately 1.4 million people in the United States alone undergo cataract surgery, whereby the clouded lens is removed and replaced with an intraocular lens (IOL) implant.
A typical IOL includes an optic or lens body for focusing light toward the retina of the eye. In addition, the IOL also includes one or more fixation members or haptics extending outward from the optic for securing and centering the IOL in the desired position within the chamber of the eye. The IOL is implanted directly into the eye through a small incision in a way that reduces trauma and expedites post-surgery healing. To fit through this small incision, modern IOLs are designed to be deformed, e.g., rolled, folded or the like, to a relatively small profile and then allowed to return to their original shape within the eye.
A useful technique for inserting an IOL into the eye includes use of an IOL injector or cartridge. Injectors for delivering IOLs into the eye typically employ a handpiece and a cartridge having a hollow insertion tube or cannula through which the folded IOL is passed using a pushrod. The cartridges are made of disposable materials, such as plastics, and remain in a sterile package until ready for coupling with the handpiece. Some injectors do without the cartridge, and may be reusable.
Conventional IOL cartridges include a load chamber connected to an injection tube. In many popular versions, such as in U.S. Pat. No. 4,681,102 to Bartell or U.S. Pat. No. 5,702,402 to Brady, the load chamber is formed by two hinged halves which receive the IOL, and which close to fold the IOL. A non-folding cartridge is seen in U.S. Pat. No. 5,474,562 to Orchowski in which forceps are used to insert the IOL into a proximal or rear opening of the cartridge. The injection tube includes a small diameter distal end that is insertable into the incision within the eye. After mating the cartridge with the handpiece (if a separate cartridge is used), the pushrod urges the IOL through the load chamber and through the injection tube into the eye. The distal end of the cartridge is beveled into a sharp point that enables insertion through the corneal incision and facilitates expulsion and manipulation of the IOL into the capsular bag. However, sometimes the IOL or the cartridge tip is damaged during the process of forcing the IOL through the cartridge tube.
In view of the above, there is a need for a cartridge that will not damage the IOL and is more robust than earlier designs.